1. Field of the Invention
The present invention relates to a scanning mechanism for moving an object to be moved in a scanning microscope.
2. Description of the Related Art
As an apparatus using a scanning mechanism, a scanning probe microscope is available. A scanning probe microscope (SPM) is a scanning microscope that obtains the information of a sample surface by mechanically scanning a probe, i.e., a mechanical probe, and includes, for example, a scanning tunneling microscope (STM), atomic force microscope (AFM), scanning magnetic force microscope (MFM), scanning capacitance microscope (SCaM), scanning near-field optical microscope (SNOM), and scanning thermal microscope (SThM).
Recently, for example, a nanoindentator designed to check the hardness and the like of a sample by pressing a diamond probe against the sample surface to make an indentation and analyzing how the indentation is formed has been regarded as one of these SPMs, and has been widely used together with the above various kinds of microscopes.
A scanning probe microscope obtains surface information on a desired sample region through the probe by making a scanning mechanism relatively scan (e.g., raster-scan) the mechanical probe and the sample in the X and Y directions. During X-Y scanning, the scanning mechanism relatively moves the mechanical probe and the sample in the Z direction as well while performing feedback control so as to, for example, stabilize the interaction between the mechanical probe and the sample. Movement in the Z direction reflects the surface configuration and/or surface condition of the sample, and hence is irregular movement, which is generally called scanning operation in the Z direction, unlike regular movement in the X and Y directions. Scanning in the Z direction is operation at the highest frequency in the X, Y, and Z directions.
The scanning frequency of the scanning probe microscope in the X direction is approximately 0.05 to 200 Hz, and the scanning frequency in the Y direction is a fraction of the number of scanning lines in the Y direction of the scanning frequency in the X direction. The number of scanning lines in the Y direction is 10 to 1,000. In addition, the scanning frequency in the Z direction ranges from a frequency corresponding to the number of pixels per line in X-direction scanning to a frequency approximately 100 times the frequency in the X scanning direction.
When, for example, an image with 100 pixels in the X direction and 100 pixels in the Y direction is to be captured in one sec, the scanning frequency in the X direction is 100 Hz; the scanning frequency in the Y direction, 1 Hz; and the scanning frequency in the Z direction, 10 kHz. A scanning mechanism that realizes this speed is proposed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2001-330425.
Recently, there has been a requirement that images be observed at the video rate. In this case, the scanning frequency required for a piezoelectric element in the Z direction is 300 kHz or more. According to the scanning mechanism disclosed in
Jpn. Pat. Appln. KOKAI Publication No. 2001-330425, a Z-direction moving actuator in charge of Z scanning comprises a stacked piezoelectric element. In order to obtain a scanning frequency of 300 kHz or more, a stacked piezoelectric element has, for example, a cubic shape with an edge of approximately 2 mm, which is very small. The stacked piezoelectric element has a very small mass of 1 g or less.
The stacked piezoelectric element is driven by application of a voltage, and hence generally two wires are connected to the element. In general, the connection of wires to the stacked piezoelectric element is performed by soldering. The connection of wires by soldering poses no serious problem with respect to a relatively large stacked piezoelectric element. However, this connection sometimes affects the displacement characteristic of a very small stacked piezoelectric element with an edge of approximately 2 mm.
In this case, a stacked piezoelectric element is exemplified. However, the piezoelectric element to be used is not limited to a stacked piezoelectric element. The same applies to a cylindrical piezoelectric element, for example, and piezoelectric elements in general.